Organic anti-reflective layer composition containing ring-opened phthalic anhydride and method for preparation thereof

ABSTRACT

A light absorbent for forming an organic anti-reflective layer, represented by the following formula 1 or formula 2, is provided: 
     
       
         
         
             
             
         
       
     
     
       
         
         
             
             
         
       
     
     wherein A represents a substituted or unsubstituted, linear or branched, saturated tetravalent hydrocarbon group, a substituted or unsubstituted, linear or branched, saturated hydrocarbon group and containing one or more heteroatoms, a substituted or unsubstituted aromatic group, a substituted or unsubstituted heteroaromatic group, a substituted or unsubstituted alicyclic group, a substituted or unsubstituted heteroalicyclic group, a substituted or unsubstituted diaryl ether, a substituted or unsubstituted diaryl sulfide, a substituted or unsubstituted diaryl sulfoxide, a substituted or unsubstituted diaryl ketone, or a substituted or unsubstituted diaryl bisphenol A; R 1 , R 2 , and R 3  each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group a substituted or unsubstituted aryl group, a substituted or unsubstituted acetal group, or a substituted or unsubstituted hydroxyl group; and n is an integer from 2 to 500.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a novel light absorbent for forming anorganic anti-reflective layer, which is a ring-opened phthalic anhydridecompound, an organic anti-reflective layer composition, a method forpatterning a semiconductor device using the organic anti-reflectivelayer composition, and a semiconductor device produced by the method forpatterning. More particularly, the present invention relates to a novellight absorbent capable of being used in producing an organicanti-reflective layer which is useful for the formation of ultrafinesemiconductor patterns using an ArF excimer laser; an organicanti-reflective layer composition containing the light absorbent, whichprevents reflection from underneath film layers in lithographicprocesses, prevents a stationary wave, and exhibits a high dry etchingrate; a method for patterning a semiconductor device using the organicanti-reflective layer composition; and a semiconductor device producedby the method for patterning.

2. Description of the Related Art

Along with the recent high integration of semiconductor devices, thereis a demand for ultrafine patterns with a line width of 0.10 micrometersor less in the production of ultra LSI and the like, and a demand alsoexists for lithographic processes using light of lower wavelengths inthe region of conventionally used g-ray or i-ray as the exposurewavelength. Accordingly, microlithographic processes using KrF excimerlasers and ArF excimer lasers are currently used for the process forproducing semiconductor devices.

Because the size of patterns of semiconductor devices is everdecreasing, only when the reflectance is maintained to be at least lessthan 1% while the exposure process is carried out, a uniform pattern canbe obtained, and an appropriate process window can be obtained, so as toattain a desired yield.

Therefore, technologies of preventing reflection from underneath filmlayers and eliminating a stationary wave, by disposing an organicanti-reflective layer containing organic molecules which are capable ofabsorbing light, beneath a photoresist layer, to thereby control thereflectance so as to reduce the reflectance at the maximum, have becomeimportant.

SUMMARY OF THE INVENTION

In order to overcome such problems as described above, it is an objectof the present invention to provide a novel light absorbent which can beused in an organic anti-reflective layer capable of absorbing reflectedlight that is generated during exposure in ultrafine patterninglithographic processes making use of 193-nm ArF excimer laser, and anorganic anti-reflective layer composition comprising the lightabsorbent.

It is another object of the invention to provide a method of designingthe basic structure of an organic anti-reflective layer to constitute achemical structure capable of increasing the etching rate of the organicanti-reflective layer, and producing a polymer in accordance therewith,to thus produce an organic anti-reflective layer using the polymer, sothat etching processes can be carried out more smoothly, and to providea method for forming a pattern of a semiconductor device using theorganic anti-reflective layer composition, which method is capable ofachieving the formation of excellent ultrafine patterns by eliminatingundercut, footing and the like.

According to an aspect of the present invention, there is provided alight absorbent for forming an organic anti-reflective layer,represented by the following formula 1:

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; and R₁ and R₂ each independently represent a hydrogenatom, a halogen atom, a substituted or unsubstituted alkyl group having1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6to 14 carbon atoms, a substituted or unsubstituted acetal group, or asubstituted or unsubstituted hydroxyl group.

According to another aspect of the present invention, there is provideda light absorbent for forming an organic anti-reflective layer,represented by the following formula 2:

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; R₃ represents a hydrogen atom, a halogen atom, asubstituted or unsubstituted alkyl group having 1 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 14 carbon atoms, asubstituted or unsubstituted acetal group, or a substituted orunsubstituted hydroxyl group; and n is an integer from 2 to 500.

According to another aspect of the present invention, there is providedan organic anti-reflective composition comprising the light absorbentrepresented by the formula 1 or formula 2, a polymer, a thermal acidgenerating agent, a crosslinking agent, and a solvent.

According to another aspect of the present invention, there is provideda method for patterning a semiconductor device, the method comprising:

applying the organic anti-reflective layer composition according to thepresent invention on top of a layer to be etched;

curing the applied composition through a baking process, and formingcrosslinking bonds to form an organic anti-reflective layer; applying aphotoresist on top of the organic anti-reflective layer, and exposingand developing the photoresist to form a photoresist pattern; and

etching the organic anti-reflective layer using the photoresist patternas an etching mask, and then etching the layer to be etched so as topattern the layer to be etched.

According to another aspect of the present invention, there is provideda semiconductor device produced by the method for patterning accordingto the present invention.

The organic anti-reflective layer composition according to the presentinvention exhibits excellent adhesiveness and storage stability, as wellas excellent resolution in both C/H patterns and L/S patterns. Theorganic anti-reflective layer composition also has an excellent processwindow, so that excellent pattern profiles can be obtained irrespectiveof the type of the substrate.

Furthermore, when a pattern is formed using the organic anti-reflectivelayer composition, etching of the anti-reflective layer can be rapidlycarried out in ultrafine patterning processes making use of a 193-nmlight source, and as a result, development of high integrationsemiconductor devices can be achieved more actively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a ¹H-NMR spectrum of a copolymer produced according to anembodiment of the present invention;

FIG. 2 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention;

FIG. 3 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention;

FIG. 4 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention;

FIG. 5 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention;

FIG. 6 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention;

FIG. 7 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention;

FIG. 8 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention; and

FIG. 9 is a ¹H-NMR spectrum of a copolymer produced according to anotherembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in more detail.

According to an aspect of the present invention, a ring-opened phthalicanhydride represented by the following formula 1, which serves as alight absorbent for forming an organic anti-reflective layer, isprovided.

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; and R₁ and R₂ each independently represent a hydrogenatom, a halogen atom, a substituted or unsubstituted alkyl group having1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6to 14 carbon atoms, a substituted or unsubstituted acetal group, or asubstituted or unsubstituted hydroxyl group.

According to another aspect of the present invention, a ring-openedphthalic anhydride compound represented by the following formula 2,which serves as a light absorbent for forming an organic anti-reflectivelayer, is provided.

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; R₃ represents a,hydrogen atom, a halogen atom, asubstituted or unsubstituted alkyl group having 1 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 14 carbon atoms, asubstituted or unsubstituted acetal group, or a substituted orunsubstituted hydroxyl group; and n is an integer from 2 to 500, andpreferably an integer from 2 to 300.

Preferably, the compound of formula 2 has a weight average molecularweight of 350 to 100,000, and more preferably 400 to 50,000.

The light absorbent contained in an organic anti-reflective layer can beclassified into a type in which the light absorbent is included in acompound in the form of a chemical moiety capable of absorbing light,and a type in which the light absorbent is separately present with apolymer incapable of absorbing light. Typically, the light absorbent isseparately used so that the amount of the light absorbing chemicalspecies can be controlled.

The light absorbent of the present invention includes a benzenechromophore, and contains functional groups for thermal curing.

Specifically, since benzene chromophore derivatives may have widelyvarying etching properties depending on the structure, derivativeshaving various structures have been introduced in the present inventionfor the application in the organic anti-reflective layer composition.

Upon examining the reaction between the above-described light absorbentaccording to the present invention and a thermally curable compoundwhich is a polymer to be contained in the anti-reflective layercomposition as will be described later, a carboxylic acid functionalgroup is generated by ring-opening of the light absorbent by means of analcohol compound, and this carboxylic acid functional group reacts witha functional group of the thermally curable compound, such as acetal,epoxy or hemiacetal, to form a crosslinked structure.

The term “substituted” according to the present invention means that oneor more hydrogen atoms in a group may be respectively substituted with ahalogen atom, a hydroxyl group, a nitro group, a cyano group, an aminogroup, an amidino group, hydrazine, hydrazone, a carboxylic acid groupor a salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₁₀ alkyl group, a C₁-C₁₀ alkenylgroup, a C₁-C₁₀ alkynyl group, a C₆-C₂₀ aryl group, a C₇-C₂₀ arylalkylgroup, a C₄-C₂₀ heteroaryl group or a C₅-C₂₀ heteroarylalkyl group.

Specific examples of the light absorbent for forming an organicanti-reflective layer, represented by the formula 1, according to thepresent invention include compounds of the following formulas 3 to 42.

Furthermore, specific examples of the light absorbent for forming anorganic anti-reflective layer, represented by the formula 2, accordingto the present invention include compounds of the following formulas 43to 60.

According to an embodiment of the present invention, the compoundsrepresented by formula 1 of the present invention are produced byreacting a substituted or unsubstituted benzyl alcohol compoundrepresented by the following formula 61 with various dianhydridecompounds in the presence of a base, and then neutralizing the base usedwith an acid.

wherein R₄ represents a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, a substituted orunsubstituted aryl group having 6 to 14 carbon atoms, a substituted orunsubstituted acetal group, or a substituted or unsubstituted hydroxylgroup.

According to another embodiment of the present invention, the compoundsrepresented by formula 2 of the present invention can be produced byreacting a compound represented by the following formula 62 with variousdianhydride compounds.

wherein R₅ represents a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group having 1 to 10 carbon atoms, a substituted orunsubstituted aryl group having 6 to 14 carbon atoms, a substituted orunsubstituted acetal group, or a substituted or unsubstituted hydroxylgroup.

The light absorbent of the present invention can be synthesized byconventional methods, but preferably, synthesis of the light absorbentof the present invention is achieved by a reaction in a basicenvironment.

The aforementioned various dianhydrides are advantageous in that thecompounds are highly reactive with alcohols, and have four reactivegroups so that two chromophores can be introduced first and then twomore crosslinking sites can be provided in the subsequent processes.

Examples of the base that can be used to provide a basic environmentinclude dimethylaminopyridine, pyridine, 1,4-diazabicyclo[2,2,2]octane.1,5-diazabicyclo[4,3,0]nonane, triethylamine, 2,6-di-tert-butylpyridine,diisopropylethylamine, diazabicycloundecene, tetramethylethylenediamine,tetrabutylammonium bromide and the like, and no particular limitation isposed.

As for the solvent for synthesis, one or more can be selected frombenzene, toluene, xylene, halogenated benzene, diethyl ether,tetrahydrofuran, esters, ethers, lactones, ketones and amides, and used.

The temperature for synthesis of the compound can be selected and usedin accordance with the solvent, and is usually 5° C. to 200° C., andpreferably 20° C. to 100° C.

According to another aspect of the present invention, an organicanti-reflective layer composition containing the light absorbent of thepresent invention is also provided.

According to an embodiment of the present invention, the organicanti-reflective layer composition comprises the light absorbent of thepresent invention, a polymer, a thermal acid generating agent, acrosslinking agent and a solvent.

A preferable organic anti-reflective layer composition needs to satisfythe following requirements.

Firstly, the composition should contain a substance which is capable ofabsorbing light in the wavelength region of the light source forexposure so as to prevent reflection from underneath film layers.

Secondly, in a process of laminating an anti-reflective layer and thenlaminating a photoresist layer, the anti-reflective layer should not bedissolved and destroyed by the solvent for the photoresist. For thisreason, the anti-reflective layer should be designed to have a structurewhich can be thermally cured, and during the process of laminating theanti-reflective layer, a baking process is carried out after coating ofthe anti-reflective layer so as to proceed curing.

Thirdly, the anti-reflective layer should be able to be etched morerapidly than the photoresist layer on the upper side, so that the lossof photoresist resulting from etching of underneath film layers can bereduced.

Fourthly, the anti-reflective layer composition should not be reactiveto the photoresist on the upper side. Further, compounds such as aminesor acids should be prevented from migrating to the photoresist layer.This is because these migrating impurities may cause defects, such asfooting or undercut in particular, in the photoresist pattern.

Fifthly, the anti-reflective layer composition should have opticalproperties which are suitable for various exposure processes usingvarious substrates, that is, appropriate refractive index and absorptioncoefficient, and should have good adhesive power to the substrate andphotoresist layer.

The organic anti-reflective layer composition according to the presentinvention satisfies all of the above-mentioned requirements.

Hereinafter, the organic anti-reflective layer composition according tothe present invention will be described in detail.

The light absorbent is a compound represented by formula 1 or formula 2as described previously in the above. The polymer to be contained in theorganic anti-reflective layer composition of the present invention canbe obtained by polymerizing an acrylate-based, maleic anhydride-based,phenol-based or ester-based monomer, and the polymer is not particularlylimited as long as it is a polymer having crosslinking sites which arecapable of reacting with the light absorbent, at the terminals of themain chain or side chains.

An organic anti-reflective layer employing such polymer acquiresresistance to dissolution by solvents, as the composition applied on asubstrate is cured while going through a baking process.

Therefore, at the time of applying a photosensitizer after thelamination of the organic anti-reflective layer, dissolution of theanti-reflective layer by the solvent of the photosensitizer does notoccur, and stability can be imparted to the anti-reflective layer.

The organic anti-reflective layer composition of the present inventionmay contain additives in order to facilitate curing of the lightabsorbent and polymer and to enhance their performance, and examples ofsuch additives include a crosslinking agent and a thermal acidgenerating agent.

First, the crosslinking agent is preferably a compound having at leasttwo or more crosslinkable functional groups, and examples thereofinclude aminoplastic compounds, polyfunctional epoxy resins, mixtures ofdianhydrides, and the like.

The aminoplastic compounds may be exemplified bydimethoxymethylglycoluril, diethoxymethylglycoluril and mixturesthereof, diethyldimethylmethylglycoluril, tetramethoxymethylglycoluril,hexamethoxymethylmelamine resin, and the like.

As for the polyfunctional epoxy compounds, it is preferable to use, forexample, MY720, CY179MA, DENACOL and the like, as well as productsequivalent thereto.

Next, it is preferable to use a thermal acid generating agent as acatalyst for accelerating the curing reaction. As for the thermal acidgenerating agent to be contained in the present invention,toluenesulfonic acid, amine salts or pyridine salts of toluenesulfonicacid, alkylsulfonic acid, amine salts or pyridine salts of alkylsulfonicacid, and the like can also be used.

As for the organic solvent that can be used in the organicanti-reflective layer composition of the present invention, it ispreferable to use one or more solvents selected from the groupconsisting of propylene glycol monomethyl ether (PGME), propylene glycolmonomethyl ether acetate (PGMEA), cyclohexanone, ethyl lactate,propylene glycol n-propyl ether, dimethylformamide (DMF),γ-butyrolactone, ethoxyethanol, methoxyethanol, methyl3-methoxypropionate (MMP) and ethyl 3-ethoxypropionate (EEP).

According to another embodiment of the present invention, the organicanti-reflective layer composition contains the light absorbentrepresented by formula 1 or formula 2 in an amount of preferably 0.1 to40% by weight, more preferably 0.1 to 15% by weight, and even morepreferably 0.1 to 10% by weight, based on the whole composition. Thepolymer is contained in an amount of preferably 0.1 to 20% by weightbased on the whole composition. The crosslinking agent is contained inan amount of preferably 0.01 to 15% by weight, and more preferably 0.05to 7% by weight, based on the whole composition. The thermal acidgenerating agent is contained in an amount of 0.01 to 20% by weight,more preferably 0.01 to 10% by weight, and even more preferably 0.02 to5% by weight, based on the whole composition. The balance of thecontents in the composition can be constituted of the solvent and otheradditional additives which are well known and widely used.

When the processes for forming an organic anti-reflective layer arebriefly examined, an organic anti-reflective layer compositioncontaining the constituent components as described above at thecompositional ratios given above is applied on a wafer, and then athermal process such as baking is carried out so that acid is generatedfrom the thermal acid generating agent. Then, in the presence of thegenerated acid, a crosslinking reaction involving the light absorbentrepresented by formula 1 or formula 2, the polymer and the crosslinkingagent which is used as an additive, is accelerated, and an organicanti-reflective layer which is not soluble in organic solvents isformed. Such organic anti-reflective layer can prevent diffusedreflection from the layers underneath the photoresist layer by absorbingfar-ultraviolet rays which have penetrated through the photoresist layerand reached the organic anti-reflective layer.

The method for forming a pattern of a semiconductor device using theorganic anti-reflective layer composition as described above, comprisesapplying the organic anti-reflective layer composition on top of a layerto be etched; curing the applied composition through a baking process,and forming crosslinking bonds to form an organic anti-reflective layer;applying a photoresist on top of the organic anti-reflective layer, andexposing and developing the photoresist to form a photoresist pattern;and etching the organic anti-reflective layer using the photoresistpattern as an etching mask, and then etching the layer to be etched soas to pattern the layer to be etched.

In the process of laminating the organic anti-reflective layer accordingto the present invention, the baking process can be carried outpreferably at a temperature of 150° C. to 250° C. for 0.5 to 5 minutes,and more preferably for 1 minute to 5 minutes.

Furthermore, in the patterning method according to the presentinvention, an additional baking process can be carried out again beforeor after laminating an organic or inorganic composition ofanti-reflective layer or silicone anti-reflective layer on top of aspin-on carbon hard mask, and such baking process is preferably carriedout at a temperature of 70° C. to 200° C.

According to another aspect of the present invention, a semiconductordevice produced by the patterning method of the present invention isprovided.

The present invention will be described specifically by way of thefollowing Synthesis Examples and Examples. However, the presentinvention is not intended to be limited to these Synthesis Examples andExamples.

In the following Synthesis Examples 1 to 10, light absorbents fororganic anti-reflective layer were synthesized.

SYNTHESIS EXAMPLE 1

50 g of bicycle[2,2,2]octene-2,3,5,6-tetracarboxylic acid dianhydride,43.57 g of benzenemethanol, 31.87 g of pyridine and 4.92 g ofdimethylaminopyridine were dissolved in 260.73 g of 1,4-dioxane, andthen the solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved again in dioxane. This solutionwas dropped in water, and a precipitate thus generated was filtered,washed several times with distilled water, and then dried, to obtain45.62 g (yield=46.6%) of a compound. The ¹H-NMR spectrum of thecopolymer produced according to Synthesis Example 1 is presented in FIG.1.

SYNTHESIS EXAMPLE 2

105 g of 4,4′-oxydiphthalic anhydride, 73.21 g of benzenemethanol, 5.36g of pyridine, and 8.27 g of dimethylaminopyridine were dissolved in450.21 g of 1,4-dioxane, and then the solution was allowed to react at80° C. for 24 hours. After completion of the reaction, formic acid wasadded dropwise to the reaction solution to neutralize the solution.Ethyl acetate and distilled water were added to this reaction product,and the organic layer was separated. The separated organic layer wassubjected to solvent removal, and then was dissolved in propylene glycolmonomethyl ether acetate, to obtain a compound. The ¹H-NMR spectrum ofthe solid light absorbent produced according to Synthesis Example 2 ispresented in FIG. 2.

SYNTHESIS EXAMPLE 3

50 g of 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride),19.74 g of benzyl alcohol, 15.2 g of pyridine, and 2.35 g ofdimethylaminopyridine were dissolved in 174.56 g of 1,4-dioxane, andthen the solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 3 is presentedin FIG. 3.

SYNTHESIS EXAMPLE 4

50 g of benzophenone-3,3′,4,4′-tetracarboxylic acid dianhydride, 33.56 gof benzyl alcohol, 24.55 g of pyridine, and 3.79 g ofdimethylaminopyridine were dissolved in 223.8 g of 1,4-dioxane, and thenthe solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 4 is presentedin FIG. 4.

SYNTHESIS EXAMPLE 5

25 g of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, 12.17 g ofbenzyl alcohol, 8.9 g of pyridine, and 1.38 g of dimethylaminopyridinewere dissolved in 94.9 g of 1,4-dioxane, and then the solution wasallowed to react at 80° C. for 24 hours. After completion of thereaction, formic acid was added dropwise to the reaction solution toneutralize the solution. Ethyl acetate and distilled water were added tothis reaction product, and the organic layer was separated. Theseparated organic layer was subjected to solvent removal, and then wasdissolved in propylene glycol monomethyl ether acetate, to obtain acompound. The ¹H-NMR spectrum of the solid light absorbent producedaccording to Synthesis Example 5 is presented in FIG. 5.

SYNTHESIS EXAMPLE 6

20 g of 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride), 5.31g of benzenedimethanol, 3.04 g of pyridine, and 0.74 g ofdimethylaminopyridine were dissolved in 57.64 g of 1,4-dioxane, and thenthe solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 6 is presentedin FIG. 6.

SYNTHESIS EXAMPLE 7

50 g of 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride),27.28 g of 4-(hydroxymethyl)benzoic acid, 15.2 g of pyridine, and 2.35 gof dimethylaminopyridine were dissolved in 174.56 g of 1,4-dioxane, andthen the solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 7 is presentedin FIG. 7.

SYNTHESIS EXAMPLE 8

50 g of 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride),31.39 g of methyl 4-(hydroxymethyl)benzoate, 15.2 g of pyridine, and2.35 g of dimethylaminopyridine were dissolved in 174.56 g of1,4-dioxane, and then the solution was allowed to react at 80° C. for 24hours. After completion of the reaction, formic acid was added dropwiseto the reaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 8 is presentedin FIG. 8.

SYNTHESIS EXAMPLE 9

50 g of 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride),23.47 g of 4-methylbenzyl alcohol, 15.2 g of pyridine, and 2.35 g ofdimethylaminopyridine were dissolved in 174.56 g of 1,4-dioxane, andthen the solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 9 is presentedin FIG. 9.

SYNTHESIS EXAMPLE 10

50 g of 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride),23.85 g of 4-hydroxybenzyl alcohol, 15.2 g of pyridine, and 2.35 g ofdimethylaminopyridine were dissolved in 174.56 g of 1,4-dioxane, andthen the solution was allowed to react at 80° C. for 24 hours. Aftercompletion of the reaction, formic acid was added dropwise to thereaction solution to neutralize the solution. Ethyl acetate anddistilled water were added to this reaction product, and the organiclayer was separated. The separated organic layer was subjected tosolvent removal, and then was dissolved in propylene glycol monomethylether acetate, to obtain a compound. The ¹H-NMR spectrum of the solidlight absorbent produced according to Synthesis Example 10 is presentedin FIG. 10.

EXAMPLE 1

Preparation of Organic Anti-Reflective Layer Composition A

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 1, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition A.

EXAMPLE 2

Preparation of Organic Anti-Reflective Layer Composition B

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 2, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition B.

EXAMPLE 3

Preparation of Organic Anti-Reflective Layer Composition C

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 3, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition C.

EXAMPLE 4

Preparation of Organic Anti-Reflective Layer Composition D

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 4, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition D.

EXAMPLE 5

Preparation of Organic Anti-Reflective Layer Composition E

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 5, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition E.

EXAMPLE 6

Preparation of Organic Anti-Reflective Layer Composition F

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 6, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition F.

EXAMPLE 7

Preparation of Organic Anti-Reflective Layer Composition G

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 7, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition G.

EXAMPLE 8

Preparation of Organic Anti-Reflective Layer Composition H

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 8, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition H.

EXAMPLE 9

Preparation of Organic Anti-Reflective Layer Composition I

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 9, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition I.

EXAMPLE 10

Preparation of Organic Anti-Reflective Layer Composition J

4 g of the light absorbent for organic anti-reflective layer produced inthe above Synthesis Example 10, 6 g of an acrylic polymer, 2 g oftetramethoxymethylglycoluril and 0.2 g of pyridinium p-toluenesulfonatewere dissolved in 987.8 g of propylene glycol monomethyl ether acetate,and then the solution was filtered through a membrane filter having apore size of 0.2 μm, to prepare an organic anti-reflective layercomposition J.

Results for measurement of properties of organic anti-reflective layersand formation of photoresist patterns

1) Stripping Test

Each of the organic anti-reflective layer compositions A to J preparedin Example 1 to 10 was applied on a silicon wafer by spin coating, andthen the coated wafer was baked on a hot plate at 230° C. for 1 minuteto form an organic anti-reflective layer. The thickness of the layer wasmeasured, and the wafer coated with the organic anti-reflective layerwas immersed for 1 minute in ethyl lactate and propylene glycolmonomethyl ether, which are solvents used for the photoresist.Subsequently, the coated wafer was baked on a hot plate at 100° C. for 1minute to completely remove the solvents, and then the thickness of theorganic anti-reflective layer was measured again. It was confirmed thatthe anti-reflective layer was insoluble in the solvents.

2) Measurement of Optical Properties

Each of the organic anti-reflective layer compositions A to J preparedin Example 1 to 10 was applied on a silicon wafer by spin coating, andthen the coated wafer was baked on a hot plate at 230° C. for 1 minuteto form an organic anti-reflective layer. The refractive index (n) at193 nm and the extinction coefficient (k) of the anti-reflective layerwere measured using a spectroscopic ellipsometer (J.A. Woollam Co.,Inc.). The measurement results are presented in Table 1.

TABLE 1 Extinction Thickness of first Refractive coefficient microthinfilm Reflectance index (n) (k) (nm) (%) Example 1 1.62 0.28 33 <0.1Example 2 1.76 0.28 24 <0.1 Example 3 1.75 0.29 24 <0.1 Example 4 1.790.33 22 <0.1 Example 5 1.69 0.37 27 <0.2 Example 6 1.67 0.28 30 <0.1Example 7 1.65 0.29 31 <0.1 Example 8 1.68 0.29 29 <0.1 Example 9 1.670.25 30 <0.1 Example 10 1.66 0.25 31 <0.1

3) Simulation of First Microthin Film

An organic anti-reflective layer was formed using each of the organicanti-reflective layer compositions A to J prepared in Example 1 to 10,and then the refractive index (n) at 193 nm and the extinctioncoefficient (k) of the anti-reflective layer were measured using aspectroscopic ellipsometer. Subsequently, the thickness of the firstmicrothin film, and the reflectance in the case of using the thicknessof the first microthin film were calculated by performing a simulationusing the values of the refractive index (n) and extinction coefficient(k) obtained from the measurement. The simulation was related to thereflectance obtainable in the case where 40 nm of silicon oxynitride wasdeposited on the silicon wafer. The software used in the simulation wasKLA Tencor FINDLE Division PROLITH, and the results are presented inTable 1.

4) Formation of Organic Anti-Reflective Layer and Photoresist Pattern

Each of the organic anti-reflective layer compositions A to J preparedin Example 1 to 10 was applied by spin coating on a silicon waferdeposited with silicon oxynitride, and then the coated wafer was bakedon a hot plate at 230° C. for 1 minute, to form an organicanti-reflective layer. Subsequently, an ArF photoresist was applied ontop of the organic anti-reflective layer, and then the coated wafer wasbaked at 100° C. for 60 seconds. Then, the photoresist was exposed usinga scanner equipment, and then the wafer was baked again at 115° C. for60 seconds. The exposed wafer was developed using a developer solutioncontaining 2.38% by weight of TMAH, to obtain a final photoresistpattern. The pattern was of L/S type with a size of 80 nm, and theresults are presented in Table 2.

TABLE 2 Energy Focus margin depth margin (%) (μm) Shape of patternExample 1 22 0.4 Perpendicular Example 2 20 0.5 Perpendicular Example 323 0.5 Perpendicular Example 4 26 0.3 Perpendicular Example 5 31 0.5Perpendicular Example 6 28 0.4 Perpendicular Example 7 27 0.4Perpendicular Example 8 26 0.5 Perpendicular Example 9 28 0.4Perpendicular Example 10 31 0.3 Perpendicular

1. A light absorbent for forming an organic anti-reflective layer,represented by the following formula 1:

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; and R₁ and R₂ each independently represent a hydrogenatom, a halogen atom, a substituted or unsubstituted alkyl group having1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6to 14 carbon atoms, a substituted or unsubstituted acetal group, or asubstituted or unsubstituted hydroxyl group.
 2. A light absorbent forforming an organic anti-reflective layer, represented by the followingformula 2:

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; R₃ represents a hydrogen atom, a halogen atom, asubstituted or unsubstituted alkyl group having 1 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 14 carbon atoms, asubstituted or unsubstituted acetal group, or a substituted orunsubstituted hydroxyl group; and n is an integer from 2 to
 500. 3. Thelight absorbent for forming an organic anti-reflective layer accordingto claim 1, wherein the light absorbent represented by the formula 1 isa compound produced by a reaction in the presence of a base.
 4. Thelight absorbent for forming an organic anti-reflective layer accordingto claim 3, wherein the base is a compound selected from the groupconsisting of dimethylaminopyridine, pyridine,1,4-diazabicyclo[2,2,2]octane, 1,5-diazabicyclo[4,3,0]nonane,triethylamine, 2,6-di-tert-butylpyridine, diisopropylethylamine,diazabicycloundecene, tetramethylethylenediamine and tetrabutylammoniumbromide.
 5. An organic anti-reflective layer composition comprising alight absorbent represented by the following formula 1 or formula 2, apolymer, a thermal acid generating agent, a crosslinking agent and asolvent:

wherein A represents a substituted or unsubstituted, linear or branched,saturated tetravalent hydrocarbon group having 1 to 20 carbon atoms, asubstituted or unsubstituted, linear or branched, saturated hydrocarbongroup having 1 to 20 carbon atoms and containing one or moreheteroatoms, a substituted or unsubstituted aromatic group having 4 to20 carbon atoms, a substituted or unsubstituted heteroaromatic grouphaving 3 to 20 carbon atoms, a substituted or unsubstituted alicyclicgroup having 4 to 20 carbon atoms, a substituted or unsubstitutedheteroalicyclic group having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl ether having 3 to 20 carbon atoms, a substituted orunsubstituted diaryl sulfide having 3 to 20 carbon atoms, a substitutedor unsubstituted diaryl sulfoxide having 3 to 20 carbon atoms, asubstituted or unsubstituted diaryl ketone having 3 to 20 carbon atoms,or a substituted or unsubstituted diaryl bisphenol A having 3 to 20carbon atoms; R₁, R₂ and R₃ each independently represent a hydrogenatom, a halogen atom, a substituted or unsubstituted alkyl group having1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6to 14 carbon atoms, a substituted or unsubstituted acetal group, or asubstituted or unsubstituted hydroxyl group; and n is an integer from 2to
 500. 6. The organic anti-reflective layer composition according toclaim 5, wherein the composition comprises 0.1 to 5% by weight of thelight absorbent, 0.1 to 5% by weight of the polymer, 0.01 to 1% byweight of the thermal acid generating agent, and 0.05 to 5% by weight ofthe crosslinking agent.
 7. The organic anti-reflective layer compositionaccording to claim 5, wherein the polymer is a resin having crosslinkingsites at the terminals of the main chain or side chains.
 8. The organicanti-reflective layer composition according to claim 5, wherein thecrosslinking agent is an aminoplastic compound, a polyfunctional epoxyresin, an anhydride or a mixture thereof, which respectively has two ormore crosslinkable functional groups.
 9. The organic anti-reflectivelayer composition according to claim 5, wherein the thermal acidgenerating agent is toluenesulfonic acid, an amine salt oftoluenesulfonci acid, a pyridine salt of toluenesulfonic acid,alkylsulfonic acid, an amine salt of alkylsulfonic acid, or a pyridinesalt of alkylsulfonic acid.
 10. The organic anti-reflective layercomposition according to claim 5, wherein the solvent is one or moreselected from the group consisting of propylene glycol monomethyl ether(PGME), propylene glycol monomethyl ether acetate (PGMEA),cyclohexanone, ethyl lactate, propylene glycol n-propyl ether,dimethylformamide (DMF), γ-butyrolactone, ethoxyethanol, methoxyethanol,methyl 3-methoxypropionate (MMP) and ethyl 3-ethoxypropionate (EEP). 11.A method for patterning a semiconductor device, the method comprising:applying the organic anti-reflective layer composition according toclaim 5 on top of a layer to be etched; curing the applied compositionthrough a baking process, and forming crosslinking bonds to form anorganic anti-reflective layer; applying a photoresist on top of theorganic anti-reflective layer, and exposing and developing thephotoresist to form a photoresist pattern; and etching the organicanti-reflective layer using the photoresist pattern as an etching mask,and then etching the layer to be etched so as to pattern the layer to beetched.
 12. The method for patterning a semiconductor device accordingto claim 11, wherein the baking process during the curing is carried outat a temperature of 150° C. to 250° C. for 0.5 minutes or 5 minutes. 13.The method for patterning a semiconductor device according to claim 11,further comprising a second baking process before or after exposingduring the forming a photoresist pattern.
 14. A semiconductor deviceproduced by the method for patterning according to claim
 11. 15. Thelight absorbent for forming an organic anti-reflective layer accordingto claim 2, wherein the light absorbent represented by the formula 2 isa compound produced by a reaction in the presence of a base.
 16. Thelight absorbent for forming an organic anti-reflective layer accordingto claim 15, wherein the base is a compound selected from the groupconsisting of dimethylaminopyridine, pyridine,1,4-diazabicyclo[2,2,2]octane, 1,5-diazabicyclo[4,3,0]nonane,triethylamine, 2,6-di-tert-butylpyridine, diisopropylethylamine,diazabicycloundecene, tetramethylethylenediamine and tetrabutylammoniumbromide.
 17. The organic anti-reflective layer composition according toclaim 6, wherein the polymer is a resin having crosslinking sites at theterminals of the main chain or side chains.
 18. The organicanti-reflective layer composition according to claim 6, wherein thecrosslinking agent is an aminoplastic compound, a polyfunctional epoxyresin, an anhydride or a mixture thereof, which respectively has two ormore crosslinkable functional groups.
 19. The organic anti-reflectivelayer composition according to claim 6, wherein the thermal acidgenerating agent is toluenesulfonic acid, an amine salt oftoluenesulfonci acid, a pyridine salt of toluenesulfonic acid,alkylsulfonic acid, an amine salt of alkylsulfonic acid, or a pyridinesalt of alkylsulfonic acid.
 20. The organic anti-reflective layercomposition according to claim 6, wherein the solvent is one or moreselected from the group consisting of propylene glycol monomethyl ether(PGME), propylene glycol monomethyl ether acetate (PGMEA),cyclohexanone, ethyl lactate, propylene glycol n-propyl ether,dimethylformamide (DMF), γ-butyrolactone, ethoxyethanol, methoxyethanol,methyl 3-methoxypropionate (MMP) and ethyl 3-ethoxypropionate (EEP).